Being it is now a closed loop system I want to run Evans waterless coolant instead of typical antifreeze. I run it in my car and its expensive but works great

Don’t complicate it man!! Bolt it on and run it…..

As you can see, No room on the bulkhead for an off engine heat exchanger.......maybe back to engine mounted? .....but I'd have to relocate power steering pump & bracket for strb. engine and also figure out some way to not block efi throttle mouth air filter......possible?

Scippy, I am in same boat as you. I want to close cool my 500 EFI's. Im thinking custom brackets, to push tank out, away from air cleaner.

maybe put the strainers in the back ? Or stringer mount them if there’s room. Yeah , lots going on in there !

I have no room for relocating the strainers, like you said "lots going on in there" ......maybe like Got Cigs thoughts on moving & mounting bracket away from the efi throttle mouth?

Also, power steering pump on strb. engine would be in the way, would have to be moved extreme left of engine..........speaking of power steering pump, just blew hydraulic line
at compression fitting from pump....several qts in the bilge!

I had a custom bracket made for my PS pump that moved it to the far side of the motor. It now basically hangs over the far stbd stringer

I think I asked you about that awhile back ..in my case it looks like the only move I can make....also, the power steering reservoir would need moving to.......a newer smaller ps pump would be more suitable.

That one line in that photo to the pump doesn't look to healthy is that what let go? If not might want to replace that before it does.